The present invention relates to head protection methods and apparatus and, more particularly, to methods and apparatus for producing a head covering that substantially enhances the protection of the wearer in the event of a single high impact force event or repeated low impact force events where the force(s) could cause concussive injury.
There are many human activities that, due to the size and speed of the participants (and their respective competitors) coupled with a more injury-inducing environment, have increased the likelihood of serious brain injury. In lieu of discussing all of these activities the present invention will be described in terms of a specific design for a football helmet and leave the reader to visualize how the present invention would function in other applications (i.e., hockey, baseball, tank operator, race driver, snow mobile operator, motorcycle operator, and the like).
Football governing authorities are attempting to legislate, via game penalties, disqualifications, and in some cases (with professional athletes) severe financial penalties, an end to concussive injuries caused by helmet-to-helmet contact. By imposing these rules the governing authorities are trying to reverse years of coaching players to “get low”, “deliver a blow”, and “drive through your opponent”. Unfortunately no legislative remedy is available for head injuries caused by high-energy helmet contact with a hard playing surface.
Football helmet design has followed an evolutionary path from: (1) close fitting soft flexible material to (2) harder close fitting inflexible material to (3) suspension Web designs with a hard inflexible outer shell to (4) today's models that incorporate a hard inflexible outer shell with attached face guards, eye shields, and a plurality of custom fitted foam and/or air filled pads located inside the outer shell. These pads, hereafter referred to as “Fit” pads, are intended to minimize relative motion between the helmet and the users head. Generally “Fit” pads are segmented to: (1) Allow assembly within the curved surface of the helmet shell, (2) Allow space for air to circulate to provide cooling and (3) Allow maximum thickness of the “Fit” pad so as to facilitate its other function as a shock absorber that attenuates impact forces acting on the helmet shell. The objective, of course, is that the impact force attenuation is sufficient enough to prevent concussive brain injury or chronic traumatic encephalopathy (CTE). Unfortunately the increasing size and speed of the players plus the faster (and harder) all weather playing surfaces have altered the situation so that the brain injury occurrence rate is unacceptable.
Most existing designs incorporate a hard, relatively inflexible outer shell and employ various schemes to create “lost motion” or compressive shock absorption between the outer shell and the head of the user. Many, in fact, do nothing more than spread out an impact force's energy and then transfer it to a form of pad system adjacent to the wearer's head. Further, the helmet manufacturer is forced to design these pads to sometimes perform double and triple duty by providing “fit” adjustment and/or wearer comfort. All these conflicting requirements place a heavy burden on the manufacturer to produce a concussion resistant helmet that performs well over the full range of potential impact events.
For example, U.S. Pat. No. 7,062,795 issued to Skiba discloses a lightweight impact resistant outer shell with a pliable foam inner layer that contacts the wearer's head. By limiting deflection of the outer shell and therefore distributing the impact force over a larger area the patent concludes that impact load is decreased. This is misleading. Spreading the force over a larger area does reduce the force per square inch but does not, in itself, reduce the total force acting on the pad system and the users head. It does however, reduce the probability of a skull fracture.
U.S. Pat. No. 4,307,471 issued to Lovell discloses a protective helmet assembly made up two shells that slide relative to each other providing impact force energy dissipation via lost motion. The disclosed design limits protection by requiring the impact force to be in alignment with the direction in which the two surfaces are allowed to slide. Wear out of the sliding mechanism (and therefore its ability to protect) is not evident to the user.
U.S. Pat. No. 5,204,998 issued to Huei-Yu Liu discloses a dual shell concept where the chamber defined by the shells contains deflatable/inflatable bellows that exchange air with the surrounding atmosphere during a complete cycle of an impact event. Particles and other contaminants in the atmosphere can degrade bellows performance.
United States Patent Application 2006/0059606 (Ferrara) discloses a two shell helmet concept separated by bellows or other compressible devices similar to Huei-Yu Liu but claims to attenuate both normal and shear forces acting on the outer shell. This patent application apparently overlooked the fact that a helmet is essentially an interrupted sphere and that relative shearing motion of the outer shell at one point (vs. the inner shell) must continue around the helmet until it reaches an edge cap or other inter-shell attachment device. This will result in transfer of shear (tangential) force to the inner shell and/or result in outer shell distortion. This “shear” distortion calls into question the structural integrity of the assembly and whether the outer shell will return to its pre-impact orientation following the impact event.
U.S. Pat. No. 6,378,140 issued to Abraham et al discloses an impact and energy absorbing device for helmets and protective gear. The invention teaches the use of coiled springs made from polymeric materials or materials such as titanium as the energy absorbing element. The spring assembly is a conventional shock absorber design that connects a shell with various plates that are attached via female slots. To protect the wearer from all possible directions the impact force may originate necessitates many small plates arrayed around the outside of the shell thereby complicating construction and adding considerable weight.
In summary there are many helmet designs that exist but all fall short in one or more of the following requirements: 1) provide adaptive impact attenuation over a full range of impact events starting at low levels where repetitive incidents over time will lead to chronic traumatic encephalopathy (CTE) and ending at high energy impact events; 2) the primary attenuation mechanism is self-contained and sealed against outside contamination; 3) after an impact force is removed the helmet envelope shape and operational attenuation mechanism will return to the pre-impact condition without need of a maintenance procedure; 4) the primary force alleviation mechanism lowers the force alleviation required of the “comfort” and/or “fit” pads adjacent to the wearer's head; and 5) the helmet must meet current operational and aesthetic standards.